ACOUSTIC NAVIGATION SYSTEM

• US 3,723,957 A
• Filed: 11/20/1970
• Issued: 03/27/1973
• Est. Priority Date: 11/20/1970
• Status: Expired due to Term

• Current Assignee: Melvin H. Damon
• Original Assignee: Melvin H. Damon
• Inventors: Damon, Melvin H.
• Primary Examiner(s): Farley, Richard A.
• Application Number:
  US05/091,315
• Time in Patent Office: 858 Days
• Field of Search: 343/110 340/3A,5R,6R
• US Class Current: 367/117
• CPC Class Codes: G01S 1/783 the signals being transmitted sequentially

Abstract

A pair of transducer arrays are aimed underwater at a small angle to each other, and a source of acoustic energy is switched back and forth between the transducers under the control of a code generator to produce a pair of nutating beams that have a complementary code. Analogs of the beams are displayed aurally aboard a vessel for distinguishing the two beams by their code signals and detecting the bisecting plane between the beams by a steady tone signal.

Claims

1. A marine acoustic navigation system comprising:

a. underwater support means;

b. a pair of directional acoustic transducer arrays arranged together on said underwater support means and aimed at a small angle to each other to produce a pair of acoustic beams directed through the water and closely straddling a plane bisecting said angle;

c. a source of oscillatory energy;

d. a code generator;

e. switching means controlled by said code generator for applying said energy alternately to said transducer arrays for predetermined intervals to form said acoustic means with complementary code patterns that are alternately nutating on and off;

f. a vessel-mounted transducer for receiving said acoustic beams and forming electric analog signals of said beams; and

g. means for aurally displaying said analog signals so that a listener can distinguish the code of one of said beams on one side of said bisector plane, and the code of the other of said beams on the other side of said bisector plane, and a steady tone on said bisector plane.

2. The navigation system of claim 1 wherein said complementary code comprises complementary letters of the Morse alphabet, and said code generator accomplishes said swItching at a normal, aural code-receiving speed.

3. The system of claim 1 wherein said acoustic energy has an ultrasonic frequency, and said shipboard receiving means includes a transducer, an oscillator having a frequency different from the frequency of said acoustic energy, and a mixer for combining signals received from said beams with a signal from said oscillator to produce an audio frequency signal for said aural display.

4. The system of claim 3 including a visual indicator for displaying said analog signal.

5. The system of claim 1 including two pairs of said transducers aimed generally vertically and arranged so that said respective bisector planes are approximately perpendicular.

6. The system of claim 5 wherein said complementary code for each pair of transducers comprises a respective pair of complementary letters of the Morse alphabet, and said code generator drives said pairs of transducers alternately for predetermined intervals at a normal, aural, code-receiving speed.

7. The system of claim 5 wherein said pairs of transducers are operated at different frequencies.

8. The system of claim 1 wherein said transducers are directed horizontally.

9. The system of claim 1 wherein said transducers are directed vertically.

10. In a marine acoustic navigation system including:

a pair of directional acoustic transducer arrays arranged underwater and aimed at a small angle to each other to produce a pair of acoustic beams directed through the water and closely straddling a plane bisecting said angle;

a source of oscillatory energy;

a code generator; and

switching means controlled by said code generator for applying said energy alternately to said transducer arrays for predetermined intervals to form said acoustic beams with complementary code patterns;

said system being characterized by;

a. a vessel-mounted transducer arranged for receiving said acoustic beams and forming electric analog signals of said beams;

b. means for aurally displaying said analog signals so that a listener can distinguish the code of one of said beams on one side of said bisector plane, and the code of the other of said beams on the other side of said bisector plane, and a steady tone on said bisector plane.